It is proposed that choline O-phosphate should exhibit a much greater specificity in clinical chemistry tests for prostatic acid phosphatase carried out to aid in the detection and diagnosis of prostatic cancer. Tests of this proposal are in progress. An experimental analytical protocol has been developed and serum acid phosphatase levels will be measured using a currently employed conventional method and the proposed method with choline O-phosphate as a substrate. The results will be compared for the extent of correlation between the two methods and with confirmed cases of prostatic cancer.